This invention relates to the gasification of finely divided solids, and more particularly, to coal gasification plants of the kind in which coal or other carbonaceous fuel is introduced into a gasifying vessel and is converted at high temperature and in the presence of oxygen, to synthesis gas and an ash by-product.
The ash by-product collects as molten slag at a low point in the gasifying vessel and must be continuously removed therefrom. Such removal is usually achieved by providing the gasifying vessel with a slag tap through which the molten material can pass. The gasification industry recognizes that the configuration of and the material of construction for the tap are determinative of tap life. Selection of the materials of construction must be made dependent upon the high temperature environment in which the tap will be used and the errosive and corrosive nature of molten slag. The tap configuration is important as it must provide for the flow of the molten slag through the tap without slag solidification around or within the tap to cause tap bridging and close-off. If the tap is configured to have a deep bore through which the molten slag must pass, then slag solidification will most likely occur as the slag within the bore is too far removed from the interior vessel temperatures and/or shielded from radiant heat coming from the vessel interior.
Various tap configurations have been suggested to reduce solidification. See, for example, U.S. Pat. No. 4,312,637.
It is an object of this invention to provide an outlet tap which resists close-off due to the solidification of molten material within the tap and/or adjacent its exterior mouth. It is a further object of this invention to provide a tap having a configuration which can be simply formed from conventional refractory materials.